Calender for paper and the like

ABSTRACT

CALENDER IN WHICH A SMALL DIAMETER CENTER ROLL HAS PRESSURE NIP COOPERATION WITH A SERIES OF OUTER LARGER DIAMETER CONTROLLED DEFLECTION ROLLS AT EQUAL SPACINGS ABOUT SAID CENTER ROLL. THE TOP ROLL OF THE SERIES OF OUTER ROLLS IS LOADED TO CONTROL THE NIP PRESSURE LEVEL. A SECOND CENTER ROLL MAY HAVE PRESSURE NIP COOPERATION WITH TWO OF THE CONTROLLED DEFLECTION ROLLS AND MAY BE ENGAGED BY A CONTROLLED DEFLECTION ROLL AT ITS BOTTOM IN EQUALLY SPACED RELATION WITH RESPECT TO THE NIPS BETWEEN THE FIRST MENTIONED CENTER ROLL AND THE TWO BOTTOM CALENDER ROLLS OF THE SERIES OF CALENDER ROLLS.

Oct. 5, 1971 o. A. BRAFFORD 3,610,137

CALENDER FOR PAPER AND THE LIKE Filed NOV. 22, 1958 INV/iN/UR Do/wuo 4. flan-wee United States Patent "ice CALENDER FOR PAPER AND THE LIKE Donald A. Bralford, Beloit, Wis., assignor to Beloit Corporation, Beloit, Wis. Filed Nov. 22, 1968, Ser. No. 778,290 Int. Cl. B30b 3/04 US. Cl. 100-161 7 Claims ABSTRACT OF THE DISCLOSURE Calender in which a small diameter center roll has pressure nip cooperation with a series of outer larger diameter controlled deflection rolls at equal spacings about said center roll. The top roll of the series of outer rolls is loaded to control the nip pressure level. A second center roll may have pressure nip cooperation with two of the controlled deflection rolls and may be engaged by a controlled deflection roll at its bottom in equally spaced relation with respect to the nips between the first mentioned center roll and the two bottom calender rolls of the series of calender rolls.

BACKGROUND OF THE INVENTION Calenders for calendering paper conventionally comprise a bottom or king roll having a highly polished peripheral surface, where the calender is used for glossing treatment, and having a series of superposed calender rolls stacked on the bottom roll. The bottom roll is usually driven by power and at least one of the superposed calender rolls may be a controlled deflection roll, in which the deflection of the roll is controlled by fluid under pressure. The controlled deflection roll in many cases may be a driven roll while the other rolls in the calender stack are usually freely rotatable. Due to the great length and weight of the rolls, there has always been a problem of deflection of the rolls, and the rolls in the stack are subject to vibration causing undesirable streaking and barring of the paper, even where the length to diameter ratio is such that it responds to load unbalance, in the SUMMARY OF THE INVENTION AN-D OBJECTS In carrying out the present invention, I provide a calender stack having a low vibration level and eliminate the deflection problems by providing a small diameter center roll for high unit pressure and rotatable about a horizontal axis, and space a series of larger diameter calender rolls about the center calender roll, and provide pressure nip cooperation between said larger diameter calender rolls and said center roll at equal circumferentially spaced points, and control the nip pressure level by loading the top calender roll.

A principal object of the present invention, therefore, is to provide a calender stack of a more compact design than former calender stacks, by utilizing a small diame- 3,6 10,137 Patented Oct. 5, 1 971 ter center roll and space a series of larger diameter calender rolls about the center roll at equal circumferential spacings, to give equal nip pressures between the calender rolls and the small diameter center roll, and to thereby reduce vibration thereof.

Another object of the invention is to reduce the deflection and vibration problems heretofore present in calender stacks, by the use of a small diameter center roll, and the spacing of larger diameter controlled deflection rolls about the center roll to give equal nip pressures, and by controlling the nip pressure level by loading the top roll of the controlled deflection rolls.

Stillanother object of the invention is to provide a paper calender of an efficient and compact design having a low vibration level and utilizing a small diameter center roll and larger diameter controlled deflection rolls, the axes of which are spaced apart to provide a better calendering finish due to the diameter ratios between the small center roll and the large diameter controlled deflection rolls.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic view schematically illustrating a calender constructed in accordance with the principles of the present invention; and

FIG. 2 is a diagrammatic view schematically illustrating a modified form in which the invention may be embodied.

DESCRIPTION OF PREFERRED EMBODIMENT OF INVENTION In FIG. 1 of the drawing, I have diagrammatically shown a calender 10 for paper and the like, comprising a center roll 11 of a relatively small diameter and a series of larger diameter calender rolls of the same diameter, including an upper roll 12 and two lower rolls 13, 13 having nip pressure cooperation with the center roll 11 at equal circumferential spacings, the centers of which calender rolls are shown in FIG. 1 as being spaced about the axis of the center roll 11, 120 apart.

The center roll 11 may be a solid roll and is shown as being a small diameter roll and is supported for rotation about a horizontal axis and may be driven from a suitable source of power in a conventional manner (not shown). The roll 11 may have a plated surface, plated with chrome or nickel, to provide a highly polished surface where the stack is used for glossing treatment.

The calender rolls 12 and 13, 13 may be controlled deflection rolls and may be driven by contact with a web W trained through the three equally spaced nips between the roll 12 and rolls 13, 13 and the center roll 11 and partially about the roll 12.

The calender rolls 12 and 13, 13 are usually freely rotatable, but under certain conditions, one or more of said rolls may also be driven rolls. The rolls 12 and 13, 13 may be supported in a conventional manner and may be mounted for retractable movement from the center roll 11, to relieve the loads between said rolls and to accommodate the threading of the web W through the nips between said rolls. The rolls 12 and 13, 13 may also be externally loaded, if required. The supports and external load relieving loading means for the rolls 12 and 13, 13 form no part of the present invention and may be of various suitable forms, so need not herein be shown or described.

The roll 12 is diagrammatically shown as having a pressure chamber 15 extending therealong, supplied with fluid under pressure through a fluid pressure line 16, under the control of suitable valve means (not shown), in a conventional manner. The pressure chamber 15 is a part of the fluid force transfer means and may form an elongated cylinder for a piston and pressure shoe (not shown) exerting pressure on the interior of the roll shell forming the roll 12, to control the deflection thereof and to load the top roll 12 and thereby control the nip pressure level. The chamber 15 may also be a type of chamber which is sealed to the interior of the roll shell (not shown) to control the deflection of the roll by the direct application of fluid force thereto as in the British patent publication to Wilsdon et al. No. 641,466. The loading of the pressure nip by the top roll 12 by controlling the deflection of said roll by fluid force transfer means is conventional, so need not herein be shown or described further.

The rolls 13, 13 may have fluid force transfer chambers 17, 17 extending therealong within the shells of said rolls and supplied with fluid under pressure through pressure lines 19, 19 under the control of suitable valve means (not shown), to control the deflection of said rolls in a manner similar to which the deflection of the roll 12 is controlled, and to equalize the pressure in the pressure nips between said rolls and the center roll 11, where required. The rolls 13, 13, however, need not be controlled deflection rolls, but may be plain solid rolls, depending upon calendering conditions.

In the present paper calender, a compact calender design has been provided having three calender nips spaced 120 apart, about the peripheral surface of the relatively small diameter center roll 11, in which the spacing of the larger diameter calender rolls about the center roll 11 gives equal nip pressures which may be controlled by loading the interior of the shell of the roll 12, and the equal spacing by the calender rolls 12 and 13, 13 about the center roll. The provision of equal nip pressures about the center roll thereby reduces vibration of the calender to a minimum, and also obviates all deflection problems in the center roll.

In the modified form of the invention shown in FIG. 2, I take the center roll 11 and the calender rolls 12 and 13, 13 and double the number of calender nips by adding a second center roll 20 of the same diameter as the center roll 11 and engage the bottom of the second calender roll 20 by a calender roll 21, the axis of rotation of which is spaced 120 from the axes of calender rolls 13, 13.

The second center roll 20 may be similar to the small diameter center roll 11, and may be driven by power in a suitable manner where required, and has pressure nip cooperation with the bottom rolls 13, 13 and may be loaded by the calender roll 21, having nip pressure cooperation with the second center roll 20.

The bottom calender roll 21 may be a controlled deflection roll and is diagrammatically shown as having a fluid force transfer chamber 22 extending therealong, centered relative to the nip between said bottom roll and the second center roll 20, and supplied with fluid under pressure through a pressure line 23, under the control of suitable valve means (not shown) in a manner similar to which the deflection of the rolls 12 and 13, 13 is controlled. The bottom roll 21 also may be supported in a conventional manner for movement toward and from the second center roll 20 to relieve the nip pressure loads between the rolls 20 and 21, and to separate the rolls to accommodate the threading of the web in the nip between said rolls, and may also be externally loaded. The second center roll 20 may also be mounted for adjustable movement toward and from the bottom controlled deflection rolls 13, 13 in cases where it is desired to relieve the nip pressures and to separate the rolls for rethreading. The supports for the second center roll 20 and bottom calender roll 21 may be of any well-known form and are no 4 part of the present invention, so need not herein be shown or described further.

With the embodiment of the invention shown in FIG. 2, three calender nips are obtained in addition to the three calender nips obtained by the form of the invention shown in FIG. 1, by adding a second center roll 20 and the controlled deflection roll 21 having nip pressure engagement with the second center roll.

While I have herein shown and described several forms in which the invention may be embodied, it may readily be understood that various other variations and modifications in the invention may be attained without departing from the spirit and scope of the novel concepts thereof.

I claim as my invention:

1. In a calender stack,

a solid small diameter center roll,

three larger diameter calender rolls spaced equally about said center roll and having nip pressure cooperation therewith at equal angular spaced locations about said center roll,

force transferring means between at least one of said rolls and said center roll and controlling the nip pres sure level between the three calender rolls and said center roll.

2. The calender stack of claim 1,

wherein the series of calender rolls comprise at least one controlled deflection roll, and

wherein the force transferring means is a fluid force transferring means extending along said controlled deflection roll for loading the nip between said controlled deflection roll and said center roll and to thereby control the nip pressure level between the three calender rolls and said center roll.

3. The calender stack of claim 1, wherein all of the calender rolls having nip pressure cooperation with the center roll are controlled deflection rolls and have force transferring means associated therewith.

4. A calender stack in accordance with claim 1, wherein the three calender rolls are controlled deflection rolls, the force transferring means is a fluid force transferring means and is associated with each calender roll and includes a fluid pressure chamber centered relative to the nip between the controlled deflection roll and the center roll, and forming a fluid force transferring means for controlling the deflection of said controlled deflection rolls, and the nip pressure level between the three calender rolls and said center roll.

5. In a calender stack,

a solid small diameter center roll,

at least three calender rolls of the same diameter spaced about said center roll and having nip pressure cooperation therewith at equal angular spaced locations about said center roll,

a second solid small diameter center roll spaced from said first mentioned center roll and having nip defining relation with respect to two of said calender rolls, and

an additional calender roll having pressure nip cooperation with said second calender roll at equal circumferentially spaced relation with respect to the nips between said second center roll and said two calender rolls, and

force transferring means between said additional calender roll and said second solid small diameter center roll.

6. A calender stack in accordance with claim 5, wherein force transferring means is associated with each calender roll for controlling the nip pressure level between said four calender rolls and said center rolls.

7. The calender stack of claim 5,

wherein the additional calender roll is a bottom roll,

wherein all of the calender rolls are controlled deflection rolls,

wherein the force transferring means is a fluid force transferring means in centered relation relative to 6 the nips between said calender rolls and said two cen- 3,364,848 1/ 1968 Muller 100-170 X ter rolls, and 3,365,774 1/1968 Kusters 100-162 X wherein fluid under pressure is supplied to said fluid 2,851,869 9/1958 Quoos et a1. 100170 X force transferring means to control deflection of said controlled deflection rolls and the pressure nips be- 5 FOREIGN PATENTS tween said rolls and said first and second center rolls. 501050 10/1966 Germany- References Cited EDWARD L. ROBERTS, Primary Examiner UNITED STATES PATENTS 10 Us. Cl. X.R- 3,230,867 1/1966 Nelson 100--170 X 100176 3,345,937 10/1967 Kusters et a1. 182 C 

